Track engine ideas

[Tareq993]

Hi, Ive been reading the pelican forums for quite a few years and find everyone to be really informative and helpfull.

I'm in the process of gathering the bits for my latest project, purely track car.
Bodywork is to be the 1974 3.0 RSR vented flairs on a 83SC tub with 930 rear arms.
Wheels 10/10.5x16" Front 13x16" Rears running slicks

Now the decision is on the powerplant. NA or Turbo? I have a bunch of bits that I have been collecting over the years.

Couple of core engines:
3.0SC engine
3.6 964 engine

Cylinders and Pistons will be replaced
Crank on the 3.6 has damaged bearing surfaces so that will probably not be used.

I plan on using pauter rods, JE pistons and LN cylinders

Stock 993TT K16 turbos
Haltec E8 or Motec M48 ecu's

I was hoping the 964 engine would be ok but because of the damaged crank I'm contemplating sticking the 3.0SC crank in it taking advantage of the 964's 100mm cylinders and twin plug heads.

What do you think of a 3.3 shortstroke twin turbo engine?
I could fabricate the intake with ITB's or use 3.2/3.6 intake

Maybe I should just get a used 3.6 crank and stick ITB's on it?

Any input would be greatly appreciated. Once again this is pure track use no street driving.

Hope to hear your input.

Thanks

[Henry Schmidt]

First, turbo power on the track is great fun but generally means increased cost of maintenance. Weight the cost before proceeding.

If the damage to the 964 crank is a spun rod , they damage can usually be repaired by simple grinding the crank to the smaller 53 mm journal used on the SC and GT3 cranks.
The crank shop can grind the journal with a large radius which will greatly improve torsional rigidity of the crank. At this point you can run a 3.0 SC rod, a GT3 Pankl titanium rod or a custom aftermarket rod. Charles @ LN makes such a rod and may have it on the shelf.

Net you can buy a GT3 crank. They a ridiculously inexpensive and are a great choice for your application. You only need to buy a custom crank pulley to make this crank work in a 964 application. Richard Clewett @ Clewett Engineering makes the pulley.

Whether building a turbo or NA engine bigger is generally better.
You've go lots to think about so way your options carefully so you only build the once.

[Tareq993]

Hi Henry,

Both main and rod journals on the crank are damaged. I'm fairly clued up on the components that are available but undecided on the type of engine to build.

I do the building of my own engines so not worried about stripping it down every year. Was wondering how to get the best bang for the buck with the parts available.

If NA they I wouldl just do a GT3 crank with 3.8 pistons, ITB's
Was thinking of the possibility of doing something different with the turbos. Ususally like to make life difficult for myself!

I'm in Bahrain and most of the cars here at track days are all very high horsepower even with the high heat. We have a few long straights on the track and the extra power helps.

Maybe build the 3.8 now and work on a twin turbo 3.0 for future silly power